The current code really tries hard to use getNewScalarValue(), which checks if
not the original value, but a possible copy or demoted value needs to be stored.
In this calling context it seems, that we _always_ use the ScalarValue that
comes from the incoming PHI node, but never any other value. As also no test
cases fail, it seems right to just drop this call to getNewScalarValue and
remove the parameters that are not needed any more.
Johannes suggested that code like this might be needed for parallel code
generation with offloading, but it was still unclear if/what exactly would
be needed. As the parallel code generation does currently not support scalars
at all, we will remove this code for now and add relevant code back when
complitng the support of scalars in the parallel code generation.
Reviewers: jdoerfert
Subscribers: pollydev, llvm-commits
Differential Revision: http://reviews.llvm.org/D12470
llvm-svn: 246389
Our code generation currently does not support scalar references to metadata
values. Hence, it would crash if we try to model scalar dependences to metadata
values. Fortunately, for one of the common uses, debug information, we can
for now just ignore the relevant intrinsics and consequently the issue of how
to model scalar dependences to metadata.
llvm-svn: 246388
This commit drops some dead code. Specifically, there is no need to initialize
the virtual memory locations of scalars in BlockGenerator::handleOutsideUsers,
the function that initalizes the escape map that keeps track of out-of-scope
uses of scalar values. We already model instructions inside the scop that
are used outside the scope (escaping instructions) as scalar memory writes at
the position of the instruction. As a result, the virtual memory location of
this instructions is already initialized when code-generating the corresponding
virtual scalar write and consequently does not need to be initialized later on
when generating the set of escaping values.
Code references:
In TempScopInfo::buildScalarDependences we detect scalar cross-statement
dependences for all instructions (including PHIs) that have uses outside of the
scop's region:
// Check whether or not the use is in the SCoP.
if (!R->contains(UseParent)) {
AnyCrossStmtUse = true;
continue;
}
We use this information in TempScopInfo::buildAccessFunctions were we build
scalar write memory accesses for all these instructions:
if (!isa<StoreInst>(Inst) &&
buildScalarDependences(Inst, &R, NonAffineSubRegion)) {
// If the Instruction is used outside the statement, we need to build the
// write access.
IRAccess ScalarAccess(IRAccess::MUST_WRITE, Inst, ZeroOffset, 1, true,
Inst);
Functions.push_back(std::make_pair(ScalarAccess, Inst));
}
Reviewers: jdoerfert
Subscribers: pollydev, llvm-commits
Differential Revision: http://reviews.llvm.org/D12472
llvm-svn: 246383
For external users, the memory locations into which we generate scalar values
may be of interest. This change introduces two functions that allow to obtain
(or create) the AllocInsts for a given BasePointer.
We use this change to simplify the code in BlockGenerators.
llvm-svn: 246285
This change allows the BlockGenerator to be reused in contexts where we want to
provide different/modified isl_ast_expressions, which are not only changed to
a different access relation than the original statement, but which may indeed
be different for each code-generated instance of the statement.
We ensure testing of this feature by moving Polly's support to import changed
access functions through a jscop file to use the BlockGenerators support for
generating arbitary access functions if provided.
This commit should not change the behavior of Polly for now. The diff is rather
large, but most changes are due to us passing the NewAccesses hash table through
functions. This style, even though rather verbose, matches what is done
throughout the BlockGenerator with other per-statement properties.
llvm-svn: 246144
The SCEVExpander cannot deal with all SCEVs Polly allows in all kinds
of expressions. To this end we introduce a ScopExpander that handles
the additional expressions separatly and falls back to the
SCEVExpander for everything else.
Reviewers: grosser, Meinersbur
Subscribers: #polly
Differential Revision: http://reviews.llvm.org/D12066
llvm-svn: 245288
The new field in the MemoryAccess allows us to track a value related
to that access:
- For real memory accesses the value is the loaded result or the
stored value.
- For straigt line scalar accesses it is the access instruction
itself.
- For PHI operand accesses it is the operand value.
We use this value to simplify code which deduced information about the value
later in the Polly pipeline and was known to be error prone.
Reviewers: grosser, Meinsersbur
Subscribers: #polly
Differential Revision: http://reviews.llvm.org/D12062
llvm-svn: 245213
This allows the code generation to continue working even if a needed
value (that is reloaded anyway) was not yet demoted. Instead of
failing it will now create the location for future demotion to memory
and load from that location. The stores will use the same location and
by construction execute before the load even if the textual order in
the generated AST is otherwise.
Reviewers: grosser, Meinersbur
Subscribers: #polly
Differential Revision: http://reviews.llvm.org/D12072
llvm-svn: 245203
This change extends the BlockGenerator to not only allow Instructions as
base elements of scalar dependences, but any llvm::Value. This allows
us to code-generate scalar dependences which reference function arguments, as
they arise when moddeling read-only scalar dependences.
llvm-svn: 244874
Even though read-only accesses to scalars outside of a scop do not need to be
modeled to derive valid transformations or to generate valid sequential code,
but information about them is useful when we considering memory footprint
analysis and/or kernel offloading.
llvm-svn: 243981
We use the branch instruction as the location at which a PHI-node write takes
place, instead of the PHI-node itself. This allows us to identify the
basic-block in a region statement which is on the incoming edge of the PHI-node
and for which the write access was originally introduced. As a result we can,
during code generation, avoid generating PHI-node write accesses for basic
blocks that do not preceed the PHI node without having to look at the IR
again.
This change fixes a bug which was introduced in r243420, when we started to
explicitly model PHI-node reads and writes, but dropped some additional checks
that where still necessary during code generation to not emit PHI-node writes
for basic-blocks that are not on incoming edges of the original PHI node.
Compared to the code before r243420 the new code does not need to inspect the IR
any more and we also do not generate multiple redundant writes.
llvm-svn: 243852
SCEVExpander, which we are using during code generation, only allows
instructions as insert locations, but breaks in case BasicBlock->end() iterators
are passed to it due to it trying to obtain the basic block in which code should
be generated by calling Instruction->getParent(), which is not defined for
->end() iterators.
This change adds an assert to Polly that ensures we only pass valid instructions
to SCEVExpander and it fixes one case, where we used IRBuilder->SetInsertBlock()
to set an ->end() insert location which was later passed to SCEVExpander.
In general, Polly is always trying to build up the CFG first, before we actually
insert instructions into the CFG sceleton. As a result, each basic block should
already have at least one branch instruction before we start adding code. Hence,
always requiring the IRBuilder insert location to be set to a real instruction
should always be possible.
Thanks Utpal Bora <cs14mtech11017@iith.ac.in> for his help with test case
reduction.
llvm-svn: 243830
Summary:
When translating PHI nodes into memory dependences during code generation we
require two kinds of memory. 'Normal memory' as for all scalar dependences and
'PHI node memory' to store the incoming values of the PHI node. With this
patch we now mark and track these two kinds of memories, which we previously
incorrectly marked as a single memory object.
Being aware of PHI node storage makes code generation easier, as we do not need
to guess what kind of storage a scalar reference requires. This simplifies the
code nicely.
Reviewers: jdoerfert
Subscribers: pollydev, llvm-commits
Differential Revision: http://reviews.llvm.org/D11554
llvm-svn: 243420
We hoist statements that are used on both branches of an if-condition, shorten
and unify some variable names and fold some variable declarations into their
only uses. We also drop a comment which just describes the elements the loop
iterates over.
No functional change intended.
llvm-svn: 243291
To reduce compile time and to allow more and better quality SCoPs in
the long run we introduced scalar dependences and PHI-modeling. This
patch will now allow us to generate code if one or both of those
options are set. While the principle of demoting scalars as well as
PHIs to memory in order to communicate their value stays the same,
this allows to delay the demotion till the very end (the actual code
generation). Consequently:
- We __almost__ do not modify the code if we do not generate code
for an optimized SCoP in the end. Thus, the early exit as well as
the unprofitable option will now actually preven us from
introducing regressions in case we will probably not get better
code.
- Polly can be used as a "pure" analyzer tool as long as the code
generator is set to none.
- The original SCoP is almost not touched when the optimized version
is placed next to it. Runtime regressions if the runtime checks
chooses the original are not to be expected and later
optimizations do not need to revert the demotion for that part.
- We will generate direct accesses to the demoted values, thus there
are no "trivial GEPs" that select the first element of a scalar we
demoted and treated as an array.
Differential Revision: http://reviews.llvm.org/D7513
llvm-svn: 238070
Upcoming revisions of isl require us to include header files explicitly, which
have previously been already transitively included. Before we add them, we sort
the existing includes.
Thanks to Chandler for sort_includes.py. A simple, but very convenient script.
llvm-svn: 236930
This options was earlier used for experiments with the vectorizer, but to my
knowledge is not really used anymore. If anybody needs this, we can always
reintroduce this feature.
llvm-svn: 232934
The BB vectorizer is deprecated and there is no point in generating code for it
any more. This option was introduced when there was not yet any loop vectorizer
in sight. Now being matured, Polly should target the loop vectorizer.
llvm-svn: 232099
When we generate code for a whole region we have to respect dominance
and update it too.
The first is achieved with multiple "BBMap"s. Each copied block in the
region gets its own map. It is initialized only with values mapped in
the immediate dominator block, if this block is in the region and was
therefor already copied. This way no values defined in a block that
doesn't dominate the current one will be used.
To update dominance information we check if the immediate dominator of
the original block we want to copy is in the region. If so we set the
immediate dominator of the current block to the copy of the immediate
dominator of the original block.
llvm-svn: 230774
This is the code generation for region statements that are created
when non-affine control flow was present in the input. A new
generator, similar to the block or vector generator, for regions is
used to traverse and copy the region statement and to adjust the
control flow inside the new region in the end.
llvm-svn: 230340
This change has two main purposes:
1) We do not use a static interface to hide an object we create and
destroy for every basic block we copy.
2) We allow the BlockGenerator to store information between calls to
the copyBB method. This will ease scalar/phi code generation
later on.
While a lot of method signatures were changed this should not cause
any real behaviour change.
Differential Revision: http://reviews.llvm.org/D7467
llvm-svn: 228443
The support is currently limited as we only allow them in the input but do
not emit them in the transformed SCoP due to the possible semantic changes.
Differential Revision: http://reviews.llvm.org/D5225
llvm-svn: 227054
SCEV based code generation has been the default for two weeks after having
been tested for a long time. We now drop the support the non-scev-based code
generation.
llvm-svn: 222978
SCEV based code generation allows Polly to detect and generate code for loops
that do not have an explicit induction variable, but only virtual induction
variables given by SCEV.
Being able to do so has two main benefits:
- We can detect more scops by default
- We require less canonicalization before Polly, which means we get closer
to our goal of not touching the IR before analyzing its properties.
Specifically, we do not need to run -polly-indvars to introduce explicit
canonical induction variables.
This switch became possible as both the isl code generation and -polly-parallel
are LNT error free with SCEV based code generation and the isl ast generator.
llvm-svn: 222113
This patch moves the SCEV based (re)generation of values before the checking for
scop-constant terms. It enables us to provide SCEV based replacements, which
are necessary to correctly generate OpenMP subfunctions when using the SCEV
based code generation.
When recomputing a new value for a value used in the code of the original scop,
we previously directly returned the same original value for all scop-constant
expressions without even trying to regenerate these values using our SCEV
expression. This is correct when the newly generated code remains fully in the
same function, however in case we want to outline parts of the newly generated
scop into subfunctions, this approach means we do not have any opportunity to
update these values in the SCEV based code generation. (In the non-SCEV based
code generation, we can provide such updates through the GlobalMap). To ensure
we have this opportunity, we first try to regenerate scalar terms with our SCEV
builder and will only return scop-constant expressions if SCEV based code
generation was not possible.
This change should not affect the results of the existing code generation
passes. It only impacts the upcoming OpenMP based code generation.
This commit also adds a test case. This test case passes before and after this
commit. It was added to ensure test coverage for the changed code.
llvm-svn: 221393
There was no good reason why this code was split accross two functions.
In subsequent changes we will change the order in which values are looked up.
Doing so would make the split into two functions even more arbitrary.
We also slightly improve the documentation.
llvm-svn: 221388
The description of the parameter value passed to -enable-polly-aligned did
not make any sense at all, but was just a leftover coming from when this option
was copied form -enable-polly-openmp. We just drop it as the option description
gives sufficient information already.
llvm-svn: 220445
This patch does not change the semantic on it's own. However, the
dependence analysis as well as dce will now use the newest available
access relation for each memory access, thus if at some point the json
importer or any other pass will run before those two and set a new
access relation the behaviour will be different. In general it is
unclear if the dependence analysis and dce should be run on the old or
new access functions anyway. If we need to access the original access
function from the outside later, we can expose the getter again.
Differential Revision: http://reviews.llvm.org/D5707
llvm-svn: 219612
This also forbids the json importer to access other memory locations
than the original instruction as we to reuse the alignment of the
original load/store.
Differential Revision: http://reviews.llvm.org/D5560
llvm-svn: 218883
Use the explicit analysis if possible, only for splitBlock we will continue
to use the Pass * argument. This change allows us to remove the getAnalysis
calls from the code generation.
llvm-svn: 215121
+ Remove the class IslGenerator which duplicates the functionality of
IslExprBuilder.
+ Use the IslExprBuilder to create code for memory access relations.
+ Also handle array types during access creation.
+ Enable scev codegen for one of the transformed memory access tests,
thus access creation without canonical induction variables available.
+ Update one test case to the new output.
llvm-svn: 214659
Commit r206510 falsely advertised to fix the load cases, even though it only
fixed the store case. This commit adds the same fix for the load case including
the missing test coverage.
llvm-svn: 206577
Even tough we may want to generate a vector load, the address from which to load
still is a scalar. Make sure even if previous address computations may have been
vectorized, that the addresses are also available as scalars.
This fixes http://llvm.org/PR19469
Reported-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
llvm-svn: 206510
This patch enables vectorization of loops containing backward array
traversal (array stride is -1).
Contributed-by: Chris Jenneisch <chrisj@codeaurora.org>
llvm-svn: 204257
PollyIRBuilder is currently just a typedef to IRBuilder<>. Consequently, this
change should not affect behavior. In subsequent patches we will extend its
functionality to emit loop.parallel metadata.
llvm-svn: 202853
We now skip the debug intrinsics which is a lot better than crashing due to
uncopied metadata references. We should step by step investigate which debug
intrinsics we can copy without trouble.
We still keep the debug location metadata.
llvm-svn: 201860
Split the old getNewValue into two parts:
1. The function "lookupAvailableValue" that return the new version of
the instruction which is already available.
2. The function calls "lookupAvailableValue", and tries to generate
the new version if it is not available yet.
llvm-svn: 187114
Orignally, we first test if a ValueMap contains a Value, and than use the
index operator to get the corresponding new value. This requires the ValueMap
to lookup the key (i.e. the old value) twice.
Now, we directly use the "lookup" function provided by DenseMap to implement
the same functionality.
llvm-svn: 185260
1. Do not allow creating new memory access record in the InstructionToAccess map
on the fly in function getAccessFor.
2. Do not allow user to modify the memory accesses returned by getAccessFor
during the code generation process.
llvm-svn: 185253
isl recently introduced isl_val as an abstract interface to represent arbitrary
precision numbers. This interface superseeds the old isl_int interface. In
contrast to the old interface which implemented arbitrary precision arithmetic
using macros that forward to the gmp library, the new library hides the math
library implementation in isl. This allows us to switch the math library used by
isl without affecting users such as Polly.
llvm-svn: 184529
In GDB when "step" through generateScalarLoad and "finish" the call, the
returned value is non NULL, however when printing the value contained in
BBMap[Load] after this stmt:
BBMap[Load] = generateScalarLoad(...);
the value in BBMap[Load] is NULL, and the BBMap.count(Load) is 1.
The only intuitive idea that I have to explain this behavior is that we are
playing with the undefined behavior of eval order of the params for the function
standing for "BBMap[Load] = generateScalarLoad()". "BBMap[Load] = " may be
executed before generateScalarLoad is called.
Here are some other possible explanations from Will Dietz <w@wdtz.org>:
The error is likely due to BBMap[Load] being evaluated first (creating
a {Load -> uninitialized } entry in the DenseMap), then
generateScalarLoad eventually accesses the same element and finds it
to be NULL (DenseMap[Old]).. Offhand I'm not sure if this is
guaranteed to be NULL or if it's uninitialized and happens to be NULL.
The same issue can also go wrong in an even worse way: the second
DenseMap access can trigger a rehash and *invalidate* the an earlier
evaluated expression (for example LHS of the assignment), leading to a
crash when performing the assignment store.
llvm-svn: 182655
Use the new cl::OptionCategory support to move the Polly options into a separate
option category. The aim is to hide most options and show by default only the
options a user needs to influence '-O3 -polly'. The available options probably
need some care, but here is the current status:
Polly Options:
Configure the polly loop optimizer
-enable-polly-openmp - Generate OpenMP parallel code
-polly - Enable the polly optimizer (only at -O3)
-polly-no-tiling - Disable tiling in the scheduler
-polly-only-func=<function-name> - Only run on a single function
-polly-report - Print information about the activities
of Polly
-polly-vectorizer - Select the vectorization strategy
=none - No Vectorization
=polly - Polly internal vectorizer
=unroll-only - Only grouped unroll the vectorize
candidate loops
=bb - The Basic Block vectorizer driven by
Polly
llvm-svn: 181295
In the classical (non -polly-codegen-scev) mode, we assume that we can always
recreate PHI nodes during code generation. This is not true. We can only
reconstruct them from the polyhedral information, in case the entire loop of the
PHI node is part of the SCoP and consequently the PHI node was translated in
the polyhedral description.
llvm-svn: 179674
After this commit, polly is clang-format clean. This can be tested with
'ninja polly-check-format'. Updates to clang-format may change this, but the
differences will hopefully be both small and general improvements to the
formatting.
We currently have some not very nice formatting for a couple of items, DEBUG()
stmts for example. I believe the benefit of being clang-format clean outweights
the not perfect layout of this code.
llvm-svn: 177796
Given the following code
for (i = 0; i < 10; i++) {
;
}
S: A[i] = 0
When code generating S using scev based code generation, we need to retrieve
the scev of 'i' at the location of 'S'. If we do not do this the scev that
we obtain will be expressed as {0,+,1}_for and will reference loop iterators
that do not surround 'S' and that we consequently do not know how to code
generate. What we really want is the scev to be instantiated to the value of 'i'
after the loop. This value is {10} and it can be code generated without
troubles.
llvm-svn: 177777
When using the scev based code generation, we now do not rely on the presence
of a canonical induction variable any more. This commit prepares the path to
(conditionally) disable the induction variable canonicalization pass.
llvm-svn: 177548
When doing SCEV based code generation, we ignore instructions calculating values
that are fully defined by a SCEV expression. The values that are calculated by
this instructions are recalculated on demand.
This commit improves the check to verify if certain instructions can be ignored
and recalculated on demand.
llvm-svn: 177313
We fix the following formatting problems found by clang-format:
- 80 cols violations
- Obvious problems with missing or too many spaces
- multiple new lines in a row
clang-format suggests many more changes, most of them falling in the following
two categories:
1) clang-format does not at all format a piece of code nicely
2) The style that clang-format suggests does not match the style used in
Polly/LLVM
I consider differences caused by reason 1) bugs, which should be fixed by
improving clang-format. Differences due to 2) need to be investigated closer
to understand the cause of the difference and the solution that should be taken.
llvm-svn: 171241
This is an incomplete implementation of the SCEV based code generation.
When finished it will remove the need for -indvars -enable-iv-rewrite.
For the moment it is still disabled. Even though it passes 'make polly-test',
there are still loose ends especially in respect of OpenMP code generation.
llvm-svn: 155717
Tobias Grosser